Tissue Profiling by Mass Spectrometry

Abstract

Matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) has become a valuable tool to address a broad range of questions in many areas of biomedical research. One such application allows spectra to be obtained directly from intact tissues, termed "profiling" (low resolution) and "imaging" (high resolution). In light of the fact that MALDI tissue profiling allows over a thousand peptides and proteins to be rapidly detected from a variety of tissues, its application to disease processes is of special interest. Matrix-assisted laser desorption/ionization (MALDI)1 mass spectrometry (MS) from intact tissues has had a major impact on the study of molecular biology and biochemistry by permitting sensitive, rapid, and molecularly specific analyses of peptides and proteins. This technology provides information on molecular weights with high mass accuracy and protein modifications such as phosphorylation and acetylation and allows for the identification of proteins by peptide sequencing combined with protein data base searches. Although a more traditional application of MALDI MS combines separation technology such as two-dimensional gels for analysis of relatively pure proteins obtained from a complex biological sample, the required procedures are lengthy. Most importantly, because these protocols involve tissue mincing and extraction, spatial localization and relative concentrations of a given protein are lost.Tissue profiling by MALDI MS can be performed on intact tissue sections for the determination of the spatial distribution of compounds and their relative expression levels without the need for molecularly specific exogenous compounds such as antibody-based reagents. Simple sample preparation protocols allow for fast and reliable analysis, typically resulting in the detection of over a thousand ion signals in the mass range of 2

Proteomic analysis of cartilage‐ and bone‐associated samples

“…Combination of these novel technologies (LCM, microarray and SELDI) is regarded as having significant clinical potential in the future [50]. Another promising histological method relies on the use of MS in tissue imaging in situ [51][52][53]. These techniques are likely to gain more momentum, as characterization of tissue and cell subproteomes have become relevant alternative to traditional whole organism proteomics also in connective tissue studies [54,55].…”

Peptidomics: The integrated approach of MS, hyphenated techniques and bioinformatics for neuropeptide analysis

“…MALDI is capable of direct tissue analysis [39,143]. This means that a quick and direct overview of the peptides present in the tissue can be obtained.…”

Proteomics and Metabolomics in Aortic Stenosis: Studying Healthy Valves for a Better Understanding of the Disease

“…For this analyses, it is indispensable a correct sample preparation in terms of chemical and structural integrity [51]. Preparation methods must avoid delocalization and degradation of the analytes so it is important to take into account several parameters such as treatment of tissue immediately after sample procurement, sectioning, sample transfer to the MALDI target plate, matrix application, and tissue storage after sectioning [52]. It is advisable the used of fresh tissue sections though sometimes it is necessary embedding the sample in gelatine or agarose to facilitate its manipulation [53][54][55].…”